Thermal Ablation of Biological Tissue

ABSTRACT

An ablation device is described comprising an introducer and an electrode array. The electrode array couples to a distal end of the introducer. The electrode array includes a center member having a distal end configured to penetrate tissue and a plurality of electrodes. Proximal and distal ends of each electrode are relatively fixed. The electrodes are dynamically configurable from a retracted state to a deployed state in which the electrodes form a relatively spherical shape in a tissue volume.

RELATED APPLICATION

This application claims priority from U.S. Patent Application No.60/486,874, filed Jul. 11, 2003.

TECHNICAL FIELD

This invention relates generally to devices and methods for tissueablation, and more particularly to the creation of spherical ablationsin biological tissue.

BACKGROUND

Standard surgical procedures such as tissue resection for use intreatment of benign and malignant tumors of the liver and other organshave several key shortcomings affecting efficacy, morbidity andmortality. A fundamental issue in these shortcomings is the inability ofthe resection to be performed in a variety of cases. To help overcomethis limitation a series of mono-polar radio frequency (RF) devices weredesigned for use in tissue ablation and resection. These mono-polardevices however have limited usefulness in typical clinical settingsbecause they are overly complex and difficult to use and result in timeconsuming procedures that can lead to auxiliary injury to patientsthrough grounding pad burs. Further, these mono-polar tissue ablationdevices are limited in the scope and size of the ablation that can becreated, and exhibit poor consistency of ablative results along with anoverall low efficiency. Consequently, there is a need for a tissueablation system that overcomes the shortcomings of these mono-polartissue ablation devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a tissue ablation device including a hand piece, a deploymentslider, a delivery member/tube, and a plurality of energy conduits in aretracted state coupled among an energy source and a distal tip, underan embodiment.

FIG. 2 is a tissue ablation device including a hand piece, a deploymentslider, a delivery member/tube, and a plurality of energy conduits in adeployed state coupled among an energy source and a distal tip, underthe embodiment of FIG. 1.

FIG. 3 is a distal portion of a tissue ablation device including adelivery member/tube and a plurality of energy conduits in a retractedstate, under the embodiment of FIG. 1.

FIG. 4 is a distal portion of a tissue ablation device including adelivery member/tube and a plurality of energy conduits in a deployedstate, under the embodiment of FIG. 1.

FIG. 5 shows an enlarged view of the distal portion of a tissue ablationdevice including a center deployment rod and a plurality of energyconduits in a deployed state, under the embodiment of FIG. 1.

FIG. 6 shows an enlarged view of the mid-section of a tissue ablationdevice including a center deployment rod and a plurality of energyconduits in a deployed state, under the embodiment of FIG. 1.

FIG. 7 shows an exploded view of the distal end of a tissue ablationdevice including a center deployment rod along with a rotated side viewof the delivery member/tube including a plurality of energy conduits anddeployment rod, and a distal tip, under the embodiment of FIG. 1.

FIG. 8 is an end view of a plurality of deployed energy conduits havingdiameters of 5, 6, and 7 centimeters (cm), under the embodiment of FIG.1.

FIG. 9 is a cross-section of an energy conduit configured for at leastone of cutting, separating, and parting tissue as it is pressed orforced against the tissue, under an embodiment.

FIG. 10 is a distal portion of a tissue ablation device including adelivery member/tube and a plurality of energy conduits in a deployedstate, under an alternative embodiment.

FIG. 11 is a distal portion of a tissue ablation device including adelivery member/tube and a plurality of energy conduits in a deployedstate, under yet another alternative embodiment.

FIG. 12 is a flow diagram of tissue ablation procedure using the tissueablation device, under an embodiment.

In the drawings, the same reference numbers identify identical orsubstantially similar elements or acts. To easily identify thediscussion of any particular element or act, the most significant digitor digits in a reference number refer to the Figure number in which thatelement is first introduced (e.g., element 108 is first introduced anddiscussed with respect to FIG. 1).

DETAILED DESCRIPTION

A tissue ablation system including numerous components and methods isdescribed herein for generating tissue ablation volumes in variousbiological tissues. The biological tissue includes tissue of a varietyof organs of the human body including the liver, spleen, kidney, lung,breast and other organs, but is not so limited. In the followingdescription, numerous specific details are introduced to provide athorough understanding of, and enabling description for, embodiments ofthe tissue ablation system. One skilled in the relevant art, however,will recognize that the tissue ablation system can be practiced withoutone or more of the specific details, or with other components, systems,etc. In other instances, well-known structures or operations are notshown, or are not described in detail, to avoid obscuring aspects of thetissue ablation system.

FIG. 1 is a tissue ablation system 100, under an embodiment. The tissueablation system 100 includes a tissue ablation device 101 coupled to atleast one energy source 112. The tissue ablation device 101 includes ahand piece 102, a deployment slider 104, a delivery member/tube 106, aplurality of energy conduits 108, and a distal tip 110, under anembodiment. The energy conduits 108, also referred to herein aselectrodes 108, are in a retracted state, but are not so limited. FIG. 2is a tissue ablation device with the energy conduits 108 in a deployedstate, under an embodiment. The tissue ablation device 101 can alsoinclude other components as known in the art and as appropriate toprocedures including the tissue ablation device 101.

The components of the tissue ablation system 100 are described in turnwith reference to FIG. 1 and FIG. 2. The hand piece 102 of the tissueablation device 101 includes a handle by which the user grips the tissueablation device 101. The hand piece 102 provides a coupling between theenergy source 112 and one or more of the energy conduits 108 which mayor may not be coupled to at least one of the hand piece 102 and theenergy source 112. The deployment slider 104 or advancement mechanism104, which in an embodiment is integral to the hand piece 102, deploysor retracts the energy conduits 108 upon actuation.

The tissue ablation device 101 also includes a delivery member/tube 106that supports placement of the energy conduits 108 in the target tissue,but is not so limited. The delivery member/tube 106 is formed usingmaterial that is at least one of electrically conductive, conditioned,and coated to allow for electrical conductivity via the electrodes. Asan example, the delivery member/tube 106 is formed using at least one ofstainless steel, nickel titanium, alloys, and plastics including Ultem,Polycarbonate, and Liquid crystal polymer, but is not so limited. Thedelivery member/tube 106 has a diameter approximately in a range of 0.05to 0.5 inches, and has a length approximately in a range of 0.1 totwenty (20) inches as appropriate for extension into a body regionappropriate to the treatment procedure. As one example, the deliverymember/tube 106 of an embodiment has a diameter of between approximately0.08 and 0.3 inches and a length between approximately two (2) andtwelve (12) inches.

The energy conduits 108 while configured appropriately for insertioninto particular tissue types, are formed from one or more materials andhave a shape, size, and pattern that supports coupling to the targettissue and allows the energy conduits 108 to deliver sufficient energyto ablate the target tissue. The energy conduits 108 include materialsselected from among conductive or plated metals and/or plastics, superalloys including shape memory alloys, and stainless steel, to name afew. The energy conduits 108 comprise nickel titanium alloy, forexample, but can be formed from any number/combination of materialsincluding stainless steel, nickel titanium, and various alloys.

The energy conduits 108 of an embodiment, which collectively may bereferred to as an electrode array 108, can have many different sizes(including lengths and diameters) depending upon the energy deliveryparameters (current, impedance, etc.) of the corresponding system. Theuse of energy conduits 108 having different diameters allows forbalancing of energy/energy density in the target tissue. Therefore, theuse of energy conduits 108 having different diameters provides a meansof control over energy balancing in the target tissue in addition to thespacing between the energy conduits 108. An outside diameter of one ormore of the energy conduits 108 of an embodiment is approximately in therange of 0.005 to 0.093 inches, but is not so limited. Further, theenergy conduits 108 of an embodiment have lengths sufficient to generateor create an ablation diameter approximately in the range of one (1) tofifteen (15) centimeters (cm), but are not so limited. As one example,the energy conduits 108 of an embodiment have an outside diameterbetween approximately 0.01 and 0.025 inches and lengths sufficient togenerate or create an ablation diameter approximately in the range ofthree (3) to nine (9) centimeters (cm).

The energy conduits 108 of various alternative embodiments can includematerials that support bending and/or shaping of the energy conduits108. Further, the energy conduits 108 of alternative embodiments caninclude non-conducting materials, coatings, and/or coverings in varioussegments and/or proportions along the shaft of the energy conduits 108as appropriate to the energy delivery requirements of the correspondingprocedure and/or the type of target tissue

The energy source 112 of an embodiment (also referred to as a generator112 or electrical generator 112) delivers pre-specified amounts ofenergy at selectable frequencies in order to ablate tissue, but is notso limited. The energy source 112 includes at least one of a variety ofenergy sources including electrical generators operating within theradio frequency (RF) range. More specifically, the energy source 112includes an RF generator operating in a frequency range of approximately375 to 650 kHz and at a current of approximately 0.1 to 5 Amps and animpedance of approximately 5 to 100 ohms, but is not so limited. As anexample, the energy source 112 of an embodiment operates at a frequencyapproximately in the range of 400 kHz to 550 kHz and at a current ofapproximately 0.5 to four (4) Amps, but is not so limited. Variations inthe choice of electrical output parameters from the energy source 112 tomonitor or control the tissue ablation process may vary widely dependingon tissue type, operator experience, technique, and/or preference.

The tissue ablation system 100 can include any number of additionalcomponents like, for example, a controller (not shown) tosemi-automatically or automatically control delivery of energy from theenergy source 112. The controller can, for example, increase the poweroutput to the energy conduits 108, control temperature when the energyconduits 108 include temperature sensors or when receiving temperatureinformation from remote sensors, and/or monitor or control impedance,power, current, voltage, and/or other output parameters. The functionsof the controller can be integrated with those of the energy source 112,can be integrated with other components of the tissue ablation system100, or can be in the form of stand-alone units coupled among componentsof the tissue ablation system 100, but are not so limited.

Moreover, the tissue ablation system 100 can include an operator display(not shown) that provides a display of heating parameters such astemperature for one or more of the energy conduits 108, impedance,power, current, timing information, and/or voltage of the energy source112 output. The functions of the display can be integrated with those ofthe energy source 112, can be integrated with other components of thetissue ablation system 100, or can be in the form of stand-alone unitscoupled among components of the tissue ablation system 100, but are notso limited.

In operation a user advances the deployment slider 104 and in responsethe energy conduits 108 are forced, or in the case of a pre-shapedenergy conduits released, from the retracted state to the deployedstate. The shape of the deployed energy conduits can, as shown in FIG.2, form a series of approximately semi-spherical segments that, whentaken together, form the outline of a sphere. The tissue ablation devicegenerates a spherical volume of ablated tissue upon application ofenergy to the deployed electrodes.

FIG. 3 is the distal portion of a tissue ablation device 101 including adelivery member/tube 106, a deployment member or rod 112, a plurality ofenergy conduits 108 in a retracted state (two energy conduits are shownfor simplicity, but the embodiment is not so limited), and a distal tip110, under the embodiment of FIG. 1. The energy conduits 108 arecoupled, either individually or collectively, to an energy source orgenerator (not shown). When the energy conduits 108 are in the retractedstate, the distal portion of the tissue ablation device presents a verystreamline profile well suited to piercing tissue andadvancement/placement in/near an area which might contain a malignant ornon-malignant tumor. By piercing the tumor the distal tip can be placedjust beyond the tumor.

FIG. 4 is the distal portion of a tissue ablation device 101 including adelivery member/tube 106, a deployment member or rod 112, a plurality ofenergy conduits 108 in a deployed state, and a distal tip 110, under theembodiment of FIG. 1. The energy conduits 108 are coupled, eitherindividually or collectively, to an energy source or generator (notshown). Following placement of the distal portion of the tissue ablationdevice in the target tissue as appropriate to the corresponding medicalprocedure, the user advances the deployment slider (not shown) to deploythe energy conduits 108, thus fully encompassing the volume of tissuedesired to be ablated.

Regarding deploying of the energy conduits 108, some or all of theenergy conduits 108 can be deployed in response to advancement of thedeployment slider. For example, all energy conduits 108 of an embodimentare deployed simultaneously in response to advancement of the deploymentslider. As another example, one set of energy conduits 108 can bedeployed to form a sphere having a first diameter while another set ofenergy conduits 108 can be deployed to form a sphere having a seconddiameter. Other alternative embodiments can use additional deploymentschemes known in the art.

The energy conduits 108 of an embodiment deliver radio frequency (RF)current to the target tissue and, as such, can be of alternatingelectrical polarity. The alternating polarity series of energy conduitsincludes various series combinations of alternating polarities. Forexample, in an embodiment using ten (10) energy conduits, thealternating polarity is: positive polarity (+), negative polarity (−),+, −, +, −, +, −, +, −. An alternative polarity series is: +, +, −, −,+, +, −, −, +, +. Another alternative polarity series is: −, −, +, +, −,−, +, +, −, −. Yet another alternative polarity series is: +, +, +, +,+, −, −, −, −, −. These examples are exemplary only, and the tissueablation system 100 described herein is not limited to ten (10)electrodes or to these alternating polarity configurations.

The energy conduits of an alternative embodiment conduct electricity ofa single electrical polarity, with the deployment rod 112 conductselectricity having an opposite polarity to that of the energy conduits.In still another alternative embodiment, the deployable energy conduitsare switched between the same electrical polarity with the deploymentrod being the other and alternating polarity between the deployableenergy conduits. In yet another alternative embodiment, the deploymentrod and deployable energy conduits are of a single electrical polarityand one or more secondary grounding pads are used therewith to providean opposite polarity member.

Various alternative embodiments can simultaneously use any number ofenergy conduits in a procedure in order to form volumes of ablatedtissue having shapes and sizes appropriate to the treatment procedure.Numerous alternatives would be recognized by those skilled in the art inview of the tissue ablation device described herein.

FIG. 5 shows a distal region or portion of a tissue ablation device 101including a center deployment rod 112, a plurality of energy conduits108 in a deployed state (two energy conduits are shown for simplicity,but the embodiment is not so limited), conduit insulators 504, and adistal tip 110, under the embodiment of FIG. 1. In support of deliveringelectrical energy of alternating polarity via the energy conduits 108,the conduit insulators 504 mechanically couple the distal ends of theenergy conduits 108 while maintaining electrical insulation between eachof the energy conduits 108. In this tissue ablation device thedeployable energy conduits 108 are coupled to the conduit insulators504. The combination of the energy conduits 108 and the conduitinsulators 504 is coupled to a non-electrically conductive retainingdisk 502 that is coupled to an electrically conductive deployment member112. Also connected to the deployment member 112 is the electricallyconductive distal tip 110 that, in this embodiment, is suitable forpiercing tissue. Advancing the deployment slider causes the deployableenergy conduits or electrodes 108 to experience a compressive load. Asthis force increases beyond the column strength of the deployable energyconduits 108, the energy conduits 108 buckle and deploy outward in acontrolled fashion.

Alternatively, the energy conduits 108 can be pre-formed to a desirableshape when fabricated of a suitable material such as a nickel titaniumalloy. Using the pre-formed electrodes, advancement of the deploymentslider permits the deployable electrodes to return to their preformedshape. The application of a small amount of energy such as RF currentcan help to facilitate the deployment of the electrodes through thetissue.

FIG. 6 shows a mid-section of a tissue ablation device 101 including adelivery member/tube 106, a deployment member 112, and a plurality ofenergy conduits 108 in a deployed state (two energy conduits are shownfor simplicity, but the embodiment is not so limited), under theembodiment of FIG. 1. The proximal end 604 of the energy conduits 108couples to an electrical insulator 602 or insulating material 602, butis not so limited.

FIG. 7 shows an exploded view of a distal region of a tissue ablationdevice 101 including a deployment member 112, a distal tip 110, and arotated side view of an energy conduit retaining disk 502, under theembodiment of FIG. 1. Although a variety of methods exists to couple thecomponents of the tissue ablation device 101 at the distal end, one suchmethod is a simple screw thread 702 configured to accept a distal end ofthe deployment member 112. Alternatively, a press or interference fitbetween mating parts or the use of various adhesives can also be used.The retaining disk 502, as described above with reference to FIG. 5, isconfigured couple to the deployment member 112 and the distal tip 110.

FIG. 8 is an end view of a tissue ablation device 101 with deployedenergy conduits 108 forming spheres having diameters of approximately 5,6, and 7 centimeters (cm), under the embodiment of FIG. 1. The tissueablation device 101 of an embodiment provides approximately uniformspacing among the energy conduits 108, but alternative embodiments maysupport any number/combination of energy conduit 108 configurations. Thetissue ablation device 101 of an embodiment supports a variety ofspherical deployment sizes by providing control over the extent to whichthe deployable energy conduits are deployed via the deployment slider,but is not so limited.

FIG. 9 is a cross-section of an energy conduit 900 configured for atleast one of cutting, separating, and parting tissue as it is pressed orforced against the tissue, under an embodiment. The energy conduit 900is used to form the energy conduits 108 described above with referenceto FIG. 1. As the energy conduits 900 are advanced from the retractedstate (FIG. 3) to the deployed or expanded state (FIG. 4), the energyconduits 900 penetrate or separate the surrounding tissue. Thispenetration is accomplished in one embodiment using energy conduits thathave a geometry suited for separating or cutting the surrounding tissue.The penetration of tissue by the energy conduits 900 in an alternativeembodiment is accomplished with the application of energy, for exampleRF energy, to the energy conduit 900 in order to facilitate cuttingthrough the tissue during advancement of the energy conduits. Anotheralternative embodiment includes the use of both an energy conduit 900having a cutting geometry along with the application of a suitableelectrical energy to the energy conduit 900.

FIG. 10 is a distal portion 1000 of a tissue ablation device including adelivery member/tube and a plurality of energy conduits A, B, C, D, E,F, and G (collectively referred to as A-G) in a deployed state, under analternative embodiment. The energy conduits A-G comprise nickel titaniumalloy, for example, but can be formed from any number/combination ofmaterials. Further, the outside diameter of the energy conduits A-G ofan embodiment is approximately in the range of 0.010 to 0.040 inches,but is not so limited.

As described above, the delivery member/tube 1006 provides sufficientsupport for placement of the energy conduits A-G. Advancement of adeployment slider (not shown) advances and deploys the energy conduitsA-G to a deployed shape. The shape of these energy conduits A-G can forma series of approximately semi-spherical segments which in thisembodiment when taken together form the outline of a sphere 1099 thatfully encompasses a volume of tissue targeted for ablation. Theapplication of RF energy to the energy conduits A-G generates orproduces a spherical volume of ablated tissue.

The energy conduits A-G of an embodiment are configured to each have analternating electrical polarity. The energy conduits of an alternativeembodiment are of a single electrical polarity, with the deliverymember/tube 1006 conducting an opposite polarity. In still anotheralternative embodiment, the energy conduits A-G are individuallyswitched between the same electrical polarity and the deliverymember/tube 1006 conducts an opposite/alternating polarity to that ofthe energy conduits A-G. In yet another alternative embodiment, thedelivery member/tube 1006 and energy conduits A-G are of a singleelectrical polarity and one or more secondary grounding pads are usedtherewith to provide an opposite polarity member.

In operation, the tissue ablation system of an embodiment deliversenergy to target tissue via the energy conduits A-G. The energyincludes, for example, radio frequency (RF) energy, but is not solimited. The energy is delivered via any of a number of techniques. Theenergy can be applied via pulsed waveforms and/or continuous waveforms,but is not so limited.

In an example procedure that includes use of the tissue ablation system,energy can be applied to energy conduits A-G during deployment of theenergy conduits A-G into the target tissue. The energy can be appliedautomatically or, alternatively, manually as a procedure progresses andas appropriate to the procedure. Also, the energy delivered to thetarget tissue can be adjusted during the procedure by adjusting any ofthe power level, the waveforms, and a combination of the power level andthe waveform.

In another example procedure that includes use of the tissue ablationsystem, energy can be applied to energy conduits A-G followingdeployment of the energy conduits A-G into the target tissue. The energycan be applied automatically or, alternatively, manually as appropriateto the procedure. Also, the energy delivered to the target tissue can beadjusted manually and/or automatically during the procedure by adjustingany of the power level, the waveforms, and a combination of the powerlevel and the waveform.

In addition to the components of the tissue ablation device 1000,various sensing techniques can be used to guide or control the progressof the tissue ablation. For example temperature sensors can be imbeddedor attached to at least one of the energy conduits A-G and the deliverymember/tube 1006 to provide feedback to a user and/or an energycontroller. Additionally, a variety of sensors can be deployed from thetissue ablation device 1000 into tissue of the target tissue.

In addition to the components of the tissue ablation systems describedabove, various sensing techniques can be used with and/or coupled to thetissue ablation system to guide or control the progress of the tissueablation. For example temperature sensors can be imbedded or attached tothe deployable energy conduits and provide feedback to a user or anenergy controller. A variety of sensors can also be deployed from thedevice into tissue within the targeted tissue, in this case a sphere.

FIG. 11 is a distal portion 1100 of a tissue ablation device including adelivery member/tube 1106, a plurality of primary energy conduits R, S,T, U, W, X, Y, Z (collectively referred to as R-Z), and a plurality ofsecondary energy conduits H, I, J, K, L, M, N, and P (collectivelyreferred to as H-P) and Q in a deployed state, under yet anotheralternative embodiment. For clarity electrodes H, I, K, M, P, S, T, U,X, Y, and Z have been omitted in the side view of the device shown inFIG. 11. The primary R-Z and secondary H-P energy conduits comprisenickel titanium alloy, for example, but can be formed from anynumber/combination of materials some of which are described above.Further, the outside diameter of the primary R-Z and secondary H-Penergy conduits of an embodiment is approximately in the range of 0.010to 0.080 inches, but is not so limited.

As described above, the delivery member/tube 1106 provides sufficientsupport for placement of the primary energy conduits R-Z. Likewise theprimary energy conduits R-Z provide sufficient support for placement ofthe secondary energy conduits H-P. While the tissue ablation device ofan embodiment deploys one secondary energy conduit from one or moredistal and/or lateral ports in a distal region of each primary energyconduit, alternative embodiments of the tissue ablation device candeploy more than one secondary energy conduit from one or more distaland/or lateral ports of each primary energy conduit. Advancement of adeployment slider (not shown) as described above advances and deploysthe energy conduits R-Z, H-P, and Q to a deployed state or shape intarget tissue. The energy conduits R-Z, H-P in a deployed state form aseries of approximately semi-spherical segments which when takentogether in this embodiment form the outline of a sphere 1199 that fullyencompasses a volume of tissue targeted for ablation. The application ofRF energy to the energy conduits R-Z, H-P, and Q generates or produces aspherical volume of ablated tissue.

The energy conduits R-Z, H-P, and Q of an embodiment are configured toeach have an alternating electrical polarity. The energy conduits of analternative embodiment conduct electrical energy of a single electricalpolarity, with the delivery member/tube 1106 conducting electricalenergy having an opposite polarity. In still another alternativeembodiment, the energy conduits H-P and R-Z are individually switchedbetween the same electrical polarity and electrode Q is coupled toconduct electrical energy of an opposite/alternating polarity to that ofthe energy conduits H-P and R-Z. In yet another alternative embodiment,all energy conduits R-Z, H-P, and Q are of a single electrical polarityand one or more secondary grounding pads are used therewith to providean opposite polarity member. In still another embodiment, electrode Q isnot present and energy passes within the remaining electrodes.

In operation, the tissue ablation system of an embodiment deliversenergy to target tissue via the energy conduits R-Z, H-P, and Q. Theenergy includes, for example, radio frequency (RF) energy, but is not solimited. The energy is delivered via any of a number of techniques, someof which are described herein. The energy can be applied via pulsedwaveforms and/or continuous waveforms, but is not so limited.

In an example procedure that includes use of the tissue ablation system,energy can be applied to energy conduits R-Z, H-P, and Q duringdeployment of the energy conduits R-Z, H-P, and Q into the targettissue. The energy can be applied automatically or, alternatively,manually as a procedure progresses and as appropriate to the procedure.Also, the energy delivered to the target tissue can be adjusted duringthe procedure by adjusting any of the power level, the waveforms, and acombination of the power level and the waveform.

In another example procedure that includes use of the tissue ablationsystem, energy can be applied to energy conduits R-Z, H-P, and Qfollowing deployment of the energy conduits R-Z, H-P, and Q into thetarget tissue. The energy can be applied automatically or,alternatively, manually as appropriate to the procedure. Also, theenergy delivered to the target tissue can be adjusted manually and/orautomatically during the procedure by adjusting any of the power level,the waveforms, and a combination of the power level and the waveform.

In addition to the components of the tissue ablation device 1100,various sensing techniques can be used to guide or control the progressof the tissue ablation. For example temperature sensors can be imbeddedor attached to at least one of the energy conduits R-Z, H-P, and Q andthe delivery member/tube 1106 to provide feedback to a user and/or anenergy controller. Additionally, a variety of sensors can be deployedfrom the tissue ablation device 1100 into tissue of the target tissue.

In addition to the components of the tissue ablation systems describedabove, various sensing techniques can be used with and/or coupled to thetissue ablation system to guide or control the progress of the tissueablation. For example temperature sensors can be imbedded or attached tothe deployable energy conduits and provide feedback to a user or anenergy controller. A variety of sensors can also be deployed from thedevice into tissue within the targeted tissue, in this case a sphere.

FIG. 12 is a flow diagram of tissue ablation procedure using the tissueablation device, under an embodiment. In operation generally a userpositions the tissue ablation device in the target biological tissue asappropriate to a medical procedure, at block 1202. Placement of thetissue ablation device in the target tissue can include the use ofvarious visualization methods such as ultrasound stenography,Computerized Tomography (CT), and Magnetic Resonance Imaging (MRI), butis not so limited.

Following placement of the device in the target tissue the user deploysthe electrodes in the target tissue, at block 1204. Power or energy isapplied to the target tissue via the electrodes, at block 1206. Theenergy generates a volume of ablated tissue having a shape and sizeappropriate to the configuration of the deployed electrodes, at block1208. The user retracts the electrodes and removes the device from thetarget tissue, at block 1210.

As described above, the tissue ablation system of an embodiment deliversenergy to target tissue via the energy conduits or electrodes. Theenergy includes, for example, radio frequency (RF) energy, but is not solimited. The energy is delivered via any of a number of techniques. Theenergy can be applied via pulsed waveforms and/or continuous waveforms,but is not so limited.

In an example procedure that includes use of the tissue ablation system,energy can be applied to energy conduits during deployment of the energyconduits into the target tissue. The energy can be applied automaticallyor, alternatively, manually as a procedure progresses and as appropriateto the procedure. Also, the energy delivered to the target tissue can beadjusted during the procedure by adjusting any of the power level, thewaveforms, and a combination of the power level and the waveform.

In another example procedure that includes use of the tissue ablationsystem, energy can be applied to energy conduits following deployment ofthe energy conduits into the target tissue. The energy can be appliedautomatically or, alternatively, manually as appropriate to theprocedure. Also, the energy delivered to the target tissue can beadjusted manually and/or automatically during the procedure by adjustingany of the power level, the waveforms, and a combination of the powerlevel and the waveform.

As described above, the application of power to the target tissue underan embodiment is controlled automatically and/or manually under a numberof procedures. A first type of procedure uses a predetermined pattern ofenergy delivery according to a time schedule. A second type of procedurevaries the application of energy to the target tissue volume inaccordance with temperature information or feedback parameters of thetissue. A third type of procedure varies the application of energy tothe target tissue volume in accordance with impedance information orfeedback parameters of the tissue in combination with elapsed time. Afourth type of procedure varies the application of energy to the targettissue volume in accordance with impedance information or feedbackparameters of the tissue. A fifth type of procedure varies theapplication of energy to the target tissue volume in accordance withtemperature and impedance information or feedback parameters of thetissue.

Note that patent and procedure selection is the responsibility of themedical professional/user and the outcome is dependent on manyvariables, including patient anatomy, pathology, and surgicaltechniques. Use of the tissue ablation device, system and methodsdescribed herein for tissue ablation can result in localized elevatedtemperatures that can cause thermal injury to the skin. In addition,tissue or organs adjacent to the tissue being ablated may be injuredthermally. To minimize the potential for thermal injury to the skin oradjacent tissues, temperature-modifying measures can be initiated at thephysician's discretion. These may include applying a sterile ice pack orsaline-moistened gauze to cool and/or separate tissues, but are not solimited.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in a sense of “including,but not limited to.” Words using the singular or plural number alsoinclude the plural or singular number respectively. Additionally, thewords “herein,” “hereunder,” “above,” “below,” and words of similarimport refer to this application as a whole and not to any particularportions of this application. When the word “or” is used in reference toa list of two or more items, that word covers all of the followinginterpretations of the word: any of the items in the list, all of theitems in the list and any combination of the items in the list.

The above description of illustrated embodiments of the tissue ablationdevices and methods is not intended to be exhaustive or to limit thesystems and methods to the precise form disclosed. While specificembodiments of, and examples for, the tissue ablation devices andmethods are described herein for illustrative purposes, variousequivalent modifications are possible within the scope of the systemsand methods, as those skilled in the relevant art will recognize. Theteachings of the tissue ablation devices and methods provided herein canbe applied to other medical systems, not only for the medical systemsdescribed above.

The elements and acts of the various embodiments described above can becombined to provide further embodiments. These and other changes can bemade to the tissue ablation devices and methods in light of the abovedetailed description.

The above references and United States Patent applications areincorporated herein by reference. Aspects of the tissue ablation devicesand methods can be modified, if necessary, to employ the systems,functions and concepts of the various patents and applications describedabove to provide yet further embodiments of the tissue ablation devicesand methods.

In general, in the following claims, the terms used should not beconstrued to limit the tissue ablation devices and methods to thespecific embodiments disclosed in the specification and the claims, butshould be construed to include all medical devices and systems thatoperate under the claims to provide tissue ablation and/or tissueresection. Accordingly, the tissue ablation devices and methods are notlimited by the disclosure, but instead the scope of the systems andmethods is to be determined entirely by the claims.

While certain aspects of the tissue ablation devices and methods arepresented below in certain claim forms, the inventors contemplate thevarious aspects of the systems and methods in any number of claim forms.Accordingly, the inventors reserve the right to add additional claimsafter filing the application to pursue such additional claim forms forother aspects of the tissue ablation devices and methods.

1. An ablation device, comprising: an introducer; and an electrode arraycoupled to a distal end of the introducer, the electrode array includinga center member having a distal end configured to penetrate tissue and aplurality of electrodes, wherein proximal and distal ends of eachelectrode are relatively fixed, wherein the plurality of electrodes aredynamically configurable from a retracted state to a deployed state inwhich the electrodes form a relatively spherical shape in a tissuevolume. 2-17. (canceled)